SYRIA. Two powerful blasts struck Damascus during morning rush hour on Thursday, killing at least 40 people, wounding dozens and prompting the UN observer chief to appeal for help to end the bloodshed ravaging Syria.

Gruesome footage of the aftermath of the powerful bombings were aired on Syrian state television, which provided a toll of at least 40 dead and 170 wounded, while blaming the attacks on "terrorists."

The Syrian Observatory for Human Rights, a Britain-based monitoring group, put the death toll at about 50, including civilians and security forces members, and said the target was an intelligence services base.

"Two explosions caused by terrorists took place on the freeway in the south of Damascus," state television said, adding the blasts occurred "as people were heading to work and children to school."

The opposition Syrian National Council said the regime of President Bashar al-Assad was behind the twin bombings, which were among the deadliest attacks in the country's 14-month uprising.

"The regime is behind this," the exile group's Samir Nashar said, adding the aim of the attacks was to warn UN observers they were in danger and to impress upon the international community that the regime was battling "terrorists."

"This is the only way for the regime to claim that what is happening in Syria is the work of terrorist gangs and that Al-Qaeda is expanding its presence in Syria," said Nashar.

The blasts took place near a nine-storey security building, the facade of which was destroyed along with several surrounding residential complexes, an AFP correspondent at the site reported.

Television showed images of a woman's charred hand on a steering wheel, her gold bracelets dangling from her wrist.

Other burnt and mangled bodies lay in the street amid the carcasses of smouldering vehicles.

Major General Robert Mood, chief of a UN observer mission in Syria, appealed for help to stop the bloodshed in the country as he visited the site of the explosions.

"This is yet another example of the suffering brought upon the people of Syria from acts of violence," the Norwegian general said.

"We, the world community, are here with the Syrian people and I call on everyone within and outside Syria to help stop this violence," he said, according to a statement.

The attacks came a day after General Mood escaped unharmed when a roadside bomb exploded as he led a team of UN observers into the southern flashpoint city of Daraa.

Ten Syrian soldiers escorting them were hurt in Wednesday's bombing, according to the UN.

Damascus has been the target of a number of bombs in past months as Assad faces a revolt against his regime which his forces are attempting to crush.

Suicide bombers hit two security service bases in the capital on December 23, killing 44 people, in attacks the regime blamed on Al-Qaeda but which the opposition said were the work of the regime itself.

Commenting after Wednesday's Daraa attack, UN leader Ban Ki-moon warned Syria's government and opposition there is only a "brief window" to avoid civil war and indicated the future of the ceasefire monitoring mission was in doubt.

Highlighting an "alarming upsurge" of roadside bombs, alongside government attacks, Ban said in New York that both sides "must realise that we have a brief window to stop the violence, a brief opportunity to create an opening for political engagement between the government and those seeking change."

He also warned that such bombings cast doubt on the future of the mission set up to monitor a truce brokered by UN-Arab League envoy Kofi Annan.

If the violence did not stop, Ban said he feared "a full-scale civil war with catastrophic effects within Syria and across the region."

China on Thursday condemned the attack on the UN observers, and called on all parties in the conflict-torn country to "stop violence."

"We call on all parties in Syria to stop violence (in)... earnest, cooperate with and support the work of the UN monitors and ensure their safety, so as to launch the political dialogue process at an early date."

The Observatory says that almost 12,000 people, mostly civilians, have been killed in Syria since the revolt, inspired by Arab Spring uprisings, broke out in March last year.

About 800 of them have died since the UN-backed truce was supposed to have taken effect on April 12.

Annan told the UN Security Council on Tuesday the priority in Syria was "to stop the killing," and expressed concern that torture, mass arrests and other human rights violations were intensifying.

The envoy said the current observers on the ground "have had a calming effect" and the deployment by the end of the month of a 300-strong team would see a "much greater impact."

MIDDLE EAST BUSINESS COMMENT & ANALYSIS

INTERNATIONAL. Washington is moving away from the strategy it has followed since the early 2000s - of being the prime military force in regional conflicts - and is shifting the primary burden of fighting to regional powers while playing a secondary role.

INTERNATIONAL. Washington is moving away from the strategy it has followed since the early 2000s - of being the prime military force in regional conflicts - and is shifting the primary burden of fighting to regional powers while playing a secondary role.